I like the list, it seems nicely balanced. But you seem to mostly battle horde armies without many Monstrous Creatures or tough vehicles?

If I may suggest some minor changes:

BUY

For the foot-slogging Terminators to more quickly arrive where they are needed (as support for the fast moving Assault and the infiltrating Scout squad) I would think about Deep-Striking them and therefore dealing out Teleport Homers to the Veteran Sergeants of the two previously mentioned squads.
The Terminators can pop a tank or a unit once they arrive and then finish off anything the Assault Marines or Scouts need help with. Without having to crawl up the field for likely 3 turns.

The Assault squad would appreciate another model in its ranks. But that's not too important.

The Lascannon Tactical squads could have Plasma Guns. Even if it's a single shot at 24" - it DOES make a difference, often. Especially since you have few weapons that pierce 3+ or better armor.

You have little anti-tank firepower. The Terminators -foot-slogging or Deep-Striking- will take their time until their Assault Cannons are there to kill any tanks, so 2 Lascannons remain. Not really very much.
You have many bodies in your list, but sometimes it pays to swap some of them for the expensive heavy weapons in a Devastator squad. They give you the Heavy Support you need.

SELL

I find Masters of Sanctity being overkill. With Commanders and Librarians the Leadership does matter and so it pays to buy the more expensive models. But the Chaplain won't need his Ld and he likely won't need 3 wounds with his invulnerable save either.

I see your Heavy Bolter Tactical squads are intended as emergency counter-attack units? It's good for them to have many bodies. But if you need spare points: I think you can safely take some here.